How can I slow down or animate time?
This is a simple addon that using the scaling principle allowed by the NLA editor to space apart key frames, making an action take place over a greater time, slowing it down.

Its features:


Auto-baking
Works on rigid bodies
Automatically scales between any given keyframes and allows variable slowing


Installation:


Go to https://github.com/FreddieRa/BlenderAddons/blob/master/Slow.py
Click on "Raw" on the top left
Then right click anywhere and click "Save page as"
Save it as "Slow.py"
Go into Blender and go to "Addons" in user preferences and click "Install from file"
Navigate to where you saved the .py, and then tick the box when it appears in Blender


How to use it:

There are two different things this can be used on, normal animations, and rigid-body simulations.

For animations:
You don't need to do anything except have at least two keyframes.

For Rigid-body simulations: All you have to do is place a keyframe (of any type) at the start and end of the section you would like reversed. This is just so you can select part of the simulation, or all of it like in the picture. Keep in mind it will be baked and so the rigid-body nature will be removed, however this can be put back in afterwards.

Upon clicking "Slow" you will be presented with 4 options:

First Slow Frame - This is the frame from which the slow-motion will start

Last Slow Frame - This is the last frame that will be in slow-motion

Slow Factor - This is how much it will be slowed down by; 1 is nothing, 2 is half as fast

Global - If this is ticked, ALL objects in the scene will be slowed down

Example: Slowing down the middle frames of a rotating cube





How it works:

This works on the principle of scaling a block of keyframes, and shifting everything over to make space for the now-larger chunk. It is baked in order to provide enough keyframes to scale.

It automatically gets the first and last keyframe of any animation and then simply selects the area between two . It also works on objects that are already baked.

Tips and Tricks;


If you want a "slo-mo" scene that the camera pans through at normal speed, copy your camera, delete it, use "Global" to slow everything, then paste your camera back in.
It works on things that are already baked, meaning that you can repeat it on the same object, allowing you to gradually get slower. This can be done by scaling initially between two values (40-80), and then again between two closer values (55-65).
Use it in conjunction with my Reverse-Time addon for awesome slow...backwards goodness (?)


So there you go, use it, mess around with it, it's all commented so you should be able to see what's going on. I welcome comments and suggested improvements.

This is only my second addon and so I will have made mistakes but I just hope this saves people "time" (aha) and can be used for interesting projects!

-Freddie